I would get a UVB bulb. I'm not an expert on Waxy's but I know that Tree Frogs need the UVB so, try that and see if it helps!
~Lauryn
I'm not sure I've heard that Tree Frogs need UVB? I also keep Grey Trees, a Green Tree and White's Tree Frog....do they need UVB light too? I haven't had any concerns with these species.